1. Field of the Invention
The present invention relates generally to fluorinated poly(phenylene ether ketone). It relates particularly to a highly optically transparent, low dielectric fluorinated poly(phenylene ether ketone), and especially to films or coatings thereof. Both the precursor and the polymer itself are novel compositions of matter.
2. Prior Art
As a class, poly(phenylene ether ketones) are thermoplastic matrix resins which are being considered for fiber-reinforced composite applications. However, these polymer systems have been difficult to produce in high molecular weight form, as has been the case for PEEK.RTM., a commercial poly(phenylene ether ether ketone) marked by ICI. (See J. P. Critchley et al, Heat Resistant Polymers, Plenum Press, New York, p. 173).
Poly(phenylene ether ketones) have not been materials of choice of thin film applications. They are by nature insoluble and cannot be solution cast into polymer films. The only known film form of the commercial product PEEK.RTM. must be extruded. The extruded film is difficult to produce and is pale to dark amber in color, depending on thickness.
State-of-the-art polymer film and coating materials used as passivant insulators and interlevel dielectrics in the area of microelectronics range in dielectric constant from approximately 3.2 to 4.0, depending upon frequency and moisture content. Although the dielectric constant of commercial poly(phenylene ether ketone) is attractively low (2.8-2.9 at 10 GHz), it has not been useful in the field of electronics because of its inability to be processed.
State-of-the-art optically transparent polymer film and coating materials used in thermal control coating systems and for other space applications have been traditionally the aromatic polyesters (such as Mylar.RTM.) or fluorinated hydrocarbons (such as FEP-Teflon.RTM.). Poly(phenylene ether ketones) have not been exploited for thin film applications in space because of their inability to be processed in the form of thin film materials and because they are not optically transparent enough to be effective at the required solar wavelength (500 nm).
Accordingly, it is a primary object of the present invention to provide a low dielectric fluorinated poly(phenylene ether ketone) film and coating material.
Another primary object of the present invention is to provide a highly optically transparent, fluorinated poly(phenylene ether ketone) film and coating material.
Another object of the present invention is to provide a processable, soluble fluorinated poly(phenylene ether ketone) film and coating material.
Another object of the present invention is to provide a highly thermally stable fluorinated poly(phenylene ether ketone) film coating material.
Another object of the present invention is to provide a fluorinated low dielectric poly(phenylene ether ketone) film and coating material having a dielectric constant near 2.4 which should find special utility in electronic applications where high electrical insulation and thermal stability are required.
Another object of the present invention is to provide a highly optically transparent fluorinated poly(phenylene ether ketone) film and coating material having high transparency at wavelengths in the visible region of the electromagnetic spectrum, such material being useful for transmitting solar energy as needed in such applications as transmitting solar energy as needed in such applications as solar cell covers or second surface mirror coatings in thermal control coating systems.